A lock for an exterior door is known from German Patent Publication DE 92 08 526 U1. This known lock has a latch bolt which can be retracted into the lock housing by means of a follower on which the latch is fastened. A further bolt is located underneath the latch bolt, which can be unlocked from the lock housing by means of a profiled cylinder. In addition, the profiled cylinder can be pulled into the latch bolt by means of a changer. Such a lock was developed for the German, or the European market.
American locks have the peculiarity that, as a rule, the latch with the follower and latch bolt are arranged at the bottom and the further bolt at the top in the lock housing. Furthermore, as a rule the further bolt is operated by means of a key on the one side and a turning knob on the other side. Such locks have properties which are comparable with the locks mentioned at the outset. However, it is not possible to couple connecting rods with such locks, by means of which supplemental lock boxes, or respectively supplemental bolts are attached, through which the resistance of the door to break-ins could be increased.